The human foot is a very complex biological mechanism. While standing, the feet carry a persons entire weight. While walking the load on a foot at heel strike is typically about one and a half times a person's body weight. When running or carrying extra weight the loads on the foot may exceed three times the body weight. The many bones, muscles, ligaments, and tendons of the foot function to absorb and dissipate the forces of impact, carry the weight of the body and other loads, and provide forces for propulsion. Properly designed shoe insoles can assist the foot in performing these functions and protect the foot from injury.
To be practical for distribution to the general public, an insole must be able to provide benefit to the user population without requiring individualized adjustment and fitting. Insoles can be optimized to address the needs of different portions of the user population. For example, insoles can be designed to accommodate the biomechanical differences between men and women.
Biomechanically men and women are very similar in most respects. They share basically the same human design, with the same number of bones, muscles, ligaments, and a torso that supports two upper and lower limbs. However, there are some biomechanical differences. The most distinguishing anatomical feature between men and women is the pelvis. To facilitate child birth, the pelvis of a woman is typically broader and rounder than that of a man. As a result, in women the thigh bone or femur approaches the knee at a greater angle than in men. This angle, called the quadriceps angle or Q-angle, is, on average, about 18 degrees in women compared to about 13 degrees in men. This angulation places greater stress at the knee joint of most women, making them more vulnerable to misalignment injuries, such as anterior cruciate ligament tears at the knee, 4th and 5th metatarsal fractures, peroneal tendonitis, iliotibial band syndrome, and other injuries. Because women also typically have narrower heels and lighter bone structure across the tri-planar axis of the foot, they are more susceptible to over use injuries and compensatory injuries when trying to reduce stress along the medial aspect of the knee joint
Women compensate for a greater Q-angle by moving their center of mass laterally to the outside to place the leg in a straighter alignment over the foot. Women also tend to pronate more than men because their foot strikes the ground in a more supinated position on the outside of their feet during foot strike.
In view of the foregoing, it would be desirable to provide an over-the-counter insole that provides cushioning adapted to the biomechanics of women.
It would also be desirable to provide an insole that provides pronation control adapted to the unique biomechanics of women.